Abstract:A novel self-aligned technique for 0.15-μm-gate-length HEMTs (high electron mobility transistors) has been demonstrated. This technology uses a 0.15-μm-long T-gate structure defined by e-beam lithography with a SiO2 sidewall to implement the self-aligned scheme. The resultant device has low source and drain resistances, low gate resistance (200 Ω/mm), and a passivating layer over the active channel. Devices with an oxide sidewall yielded an fT of 177 GHz, whereas devices with no sidewall exhibited an fT greater than 250 GHz. The difference has been related to process damage during plasma deposition of SiO2.